Just a few years ago, Kirloskar Brothers Limited (KBL) would have needed a couple of months at the very least, to deliver a 3.2 ton Pelton Runner to their discerning clientele. However, thanks to the 3D printing technology from voxeljet, KBL can deliver these castings and such others in a matter of weeks. The VX4000, an industrial printing system from voxeljet is ideally suited to the dimensions of the sand molds required by KBL.
KBL`s challenge always is to meet extremely short timelines for critical projects with complicated geometries that require high accuracy and repeatability, e.g. spare parts.
Not only do the conventional patterns and core boxes take months to manufacture but also, it is almost impossible to maintain integrity of critical geometries by traditional processes, thereby losing an achievable product efficiency.
In order to design more flexible, more efficient products, save time and optimise their manufacturing process in a sustainable way, KBL decided to look for alternative manufacturing methods compared to traditional ones. They found their solution in 3D printing. With the help of this technology, sand casting molds and cores can be produced quickly, on-demand, cost effectively and without the need for tooling. The VX4000, with a job box size of 4.000 x 2.000 x 1.000 mm, was a ready match for the kind of products that KBL wanted to manufacture.
In case of the Pelton Runner, the complete mold set including the cope, drag and 18 bucket cores, a total of 5.700 kg, in silica sand and furan binder, were 3d printed in a matter of just 72 hours. Except KBL`s customary coating no other post processing was required. The mold was ready for assembly and casting immediately thereafter. Experience and expertise of the KBL-team in assembling this rather complicated mold was pivotal.
KBL, casted this 2.000 mm diameter Pelton Runner in CA6NM with a yield of 56%.
“Thanks to 3d printing, we have reduced our delivery times drastically. Conventional production of critical molds and cores would usually take months. Now, we have molds ready for casting in just a couple of days. We use 3d printed molds for all castings that require close dimensional accuracy, very short lead times or simply small batch sizes. At KBL we are also very happy to achieve repeatability and better surface finishes with 3D printed molds.” says Mr. Birajdar, VP & Head Corporate Research Engineering & Development, at KBL.
KBL also utilizes 3D printing to make integral cores of impellers, bowls and Francis runners which are almost impossible with conventional core boxes.
“3D printing significantly reduces delivery times and costs. At our service centre in Germany, we operate, among others, three VX4000 printing systems. This enables us to offer our customers a total print volume of up to 400 tons per month. Given the enormous component sizes and the associated volume required by KBL, the VX4000 is the world’s only 3d printing system for the economical and efficient production of the demanded sand molds,” explains Alexander Kudernatsch, Vice President Services at voxeljet AG. In India, KBL was the first company to pioneer the use of 3D printed sand molds. “It is impressive to see the mold sizes that KBL manages to create with our 3D printing technology.” says Kudernatsch.